Animal Model will provide all mice used and it will be responsible for ordering mice, performing the various manipulations required to induce experimental colitis, maintaining a barrier facility, performing routine surveys to ensure absence of pathogens in the colony, and assist in harvesting tissues from such mice. Centralization of these functions provides uniformity and quality control of mice being studied in the various projects, reduces cost, and will help conserve numbers of mice required by ensuring their optimal use in the projects. A second aim is that of centralized pathologic analyses which will be performed by Dr. Trenton Schoeb, an expert veterinary pathologist. Tissue sections from the various projects will be coded prior to interpretation and quantitative scoring where needed. This facilitates interactions among the projects and also the comparison of results. A third purpose is to provide genetically modified transgenic and knockout mouse strains for use in experiments. Such genetically altered strains are powerful analytic tools for defining the role of specific gene products in complex biologic systems, and have become the "reagents" that allow fundamental questions to be experimentally addressed that had been previously unapproachable. Mice with induced mutations frequently have to be bred onto other background strains for optimal study, which requires screening of individual animals in each generation by identification of one or more target genetic elements. Dr. Charles Elson will serve as Director and Dr. Casey Weaver will serve as Co-Director. Mice will be housed under barrier conditions in a new vivarium which is physically linked to the new Shelby Research Building. Dr. Sam Gartner from the Department of Comparative Medicine will serve as Consultant An Oversight Committee consisting of the PI of each project with Drs. Schoeb and Gartner will oversee the usage and function.